Backup power source



FIG. 1 is a perspective view of a backup power source showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left side elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a top plan view thereof;

FIG. 7 is a bottom plan view thereof;

FIG. 8 is a bottom perspective view thereof; and,

FIG. 9 is an exploded perspective view thereof.

The broken lines shown are included for the purpose of illustrating environmental structure and form no part of the claimed design. 

CLAIM The ornamental design for a backup power source, as shown and described. 